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| United States Patent |
5,157,071
|
|
Ingle
|
October 20, 1992
|
Paints and polymers for use therein
Abstract
Wet adhesion, ICI viscosity, and scrub resistance of a paint are improved
by incorporating into the paint a binder that comprises a film former and
polymeric composition. The polymeric composition comprises either (a)
about 15 to about 35 weight percent of substantially
non-self-polymerizable monomer, about 30 to about 70 weight percent of a
copolymerizable monomer whose homopolymer is water-soluble, and about 10
to about 35 weight percent of a wet adhesion promoting monomer, or (b)
about 35 to about 65 weight percent of the substantially
non-self-polymerizable monomer and about 35 to about 65 weight percent of
the wet adhesion promoting monomer. The polymeric composition and film
former are substantially inseparable by chromatographic means.
| Inventors:
|
Ingle; David M. (Hillsborough, NC)
|
| Assignee:
|
Union Oil Company of California (Los Angeles, CA)
|
| Appl. No.:
|
774730 |
| Filed:
|
October 9, 1991 |
| Current U.S. Class: |
524/516; 524/521; 524/523; 524/548; 524/551; 524/552; 524/555; 524/556; 524/558; 524/559; 524/808; 524/809; 524/812; 524/813; 524/818; 524/827; 524/832; 524/833 |
| Intern'l Class: |
C08L 027/06; C08L 039/04; 827; 832; 833 |
| Field of Search: |
524/516,519,522,523,525,528,548,555,558,521,551,552,556,559,808,809,812,813,818
|
References Cited
U.S. Patent Documents
| Re31936 | Jul., 1985 | Sperry et al. | 524/522.
|
| 3509085 | Apr., 1970 | Sekmakas | 526/263.
|
| 3843584 | Oct., 1974 | Turck | 526/318.
|
| 4172177 | Oct., 1979 | Sato | 526/312.
|
| 4219454 | Aug., 1980 | Iacoviello et al. | 526/331.
|
| 4395524 | Jul., 1983 | Emmons et al. | 526/307.
|
| 4522972 | Jun., 1985 | Mondt et al. | 524/555.
|
| 4632957 | Dec., 1986 | Welsh et al. | 524/548.
|
| 4647396 | Mar., 1987 | Denzinger et al. | 526/318.
|
| 4722965 | Feb., 1988 | Wong et al. | 526/302.
|
| 4725655 | Feb., 1988 | Denzinger et al. | 526/318.
|
| 4737549 | Apr., 1988 | Bomer et al. | 526/318.
|
| 4808660 | Feb., 1989 | Schmeing et al. | 524/812.
|
| 4855349 | Aug., 1989 | Ingle | 524/432.
|
| Foreign Patent Documents |
| 0302588 | Aug., 1989 | EP.
| |
Other References
Grant, J., "Hackh's Chemical Dictionary", 4th Ed. McGraw-Hill, New York,
1969, p. 703.
ASTM D 2486-74a.
|
Primary Examiner: Schofer; Joseph L.
Assistant Examiner: Delmendo; R. H.
Attorney, Agent or Firm: Wirzbicki; Gregory F., Frieman; Shlomo R.
Parent Case Text
This application is a continuation, of application Ser. No. 07/400,124,
filed Aug. 29, 1989, now abandoned.
Claims
What is claimed is:
1. An aqueous polymeric composition formed by reacting in water and in the
presence of an initiator:
(a) about 15 to about 35 weight percent of a substantially
non-self-polymerizable monomer selected from the group consisting of
itaconic acid, maleic acid, fumaric acid, itaconate ester, maleate ester,
fumarate ester, and mixtures thereof;
(b) about 40 to about 70 weight percent of a copolymerizable monomer
selected from the group consisting of N-vinyl lactams having the formula
##STR10##
wherein m is an integer from about 3 to about 5; acrylates having the
formula
##STR11##
and acrylamides having the formula
##STR12##
wherein R.sub.5 and R.sub.6 are independently hydrogen or methyl, R.sub.7
is hydrogen or an alkyl group, n is an integer from 1 to about 30, and p
is either 0 or 1; and
(c) about 10 to about 35 weight percent of a wet adhesion promoting monomer
selected from the group consisting of ethyleneureido-containing monomers,
cyanoacetoxy-containing monomers, acetoacetoxy-containing monomers, and
hydroxymethyl diacetone acrylamide, wherein the non-self-polymerizable
monomer, the copolymerizable monomer, and the wet adhesion promoting
monomer constitute at least 98 weight percent of the monomers employed in
forming the aqueous polymeric composition.
2. The aqueous polymeric composition of claim 1 wherein the
non-self-polymerizable monomer is selected from the group consisting of
itaconic acid, maleic acid, fumaric acid, and mixtures thereof.
3. The aqueous polymeric composition of claim 2 formed by reacting about 20
to about 30 weight percent of the non-self-polymerizable monomer, about 40
to about 60 weight percent of the copolymerizable monomer, and about 15 to
about 30 weight percent of the wet adhesion promoting monomer.
4. The aqueous polymeric composition of claim 2 wherein R.sub.7 is hydrogen
and n is 1.
5. The aqueous polymeric composition of claim 2 wherein the copolymerizable
monomer is selected from the group consisting of 2-hydroxyethyl acrylate,
2-hydroxyethyl methacrylate, and mixtures thereof.
6. The aqueous polymeric composition of claim 2 wherein the wet adhesion
promoting monomer is an ethyleneureido-containing monomer selected from
the group consisting of 2-ethyleneureido-ethyl acrylate,
2-ethyleneureido-ethyl methacrylate, 2-ethyleneureido-ethyl acrylamide,
2-ethyleneureido-ethyl methacrylamide,
1-[2-(3-allyloxy-2-hydroxypropylamino)ethyl]imidazolidin-2-one, and
mixtures thereof.
7. An aqueous binder composition comprising:
(a) the aqueous polymeric composition of claim 2;
(b) a high molecular weight film former, wherein the aqueous polymeric
composition has a solids content and, based upon the total solids content
of the aqueous binder composition, the aqueous binder composition
comprises about 0.5 to about 3 weight percent of the aqueous polymeric
composition solids content and about 97 to about 99.5 weight percent of
the high molecular weight film former.
8. An aqueous polymeric composition formed by reacting in water and in the
presence of an initiator;
(a) 35 to about 65 weight percent of a substantially non-self-polymerizable
monomer selected from the group consisting of itaconic acid, maleic acid,
fumaric acid, itaconate ester, maleate ester, fumarate ester, and mixtures
thereof; and
(b) about 35 to about 65 weight percent of a wet adhesion promoting monomer
selected from the group consisting of ethyleneureido-containing monomers,
cyanoacetoxy-containing monomers, acetoacetoxy-containing monomers, and
hydroxymethyl diacetone acrylamide, wherein the non-self-polymerizable
monomer and the wet adhesion promoting monomer constitute at least 98
weight percent of the monomers employed in forming the aqueous polymeric
composition.
9. The aqueous polymeric composition of claim 8 wherein the
non-self-polymerizable monomer is selected from the group consisting of
itaconic acid, maleic acid, fumaric acid, and mixtures thereof.
10. An aqueous polymeric composition formed by reacting in water and in the
presence of an initiator:
(a) about 15 to about 35 weight percent of a substantially
non-self-polymerizable monomer selected from the group consisting of
itaconic acid, maleic acid, fumaric acid, and mixtures thereof;
(b) about 30 to about 70 weight percent of a copolymerizable monomer
selected from the group consisting of N-vinyl lactams having the formula
##STR13##
wherein m is an integer from about 3 to about 5; acrylates having the
formula
##STR14##
and acrylamides having the formula
##STR15##
wherein R.sub.5 and R.sub.6 are independently hydrogen or methyl, R.sub.7
is hydrogen or an alkyl group, n is an integer from 1 to about 30, and p
is either 0 or 1;
(c) about 10 to about 35 weight percent of a wet adhesion promoting monomer
selected from the group consisting of ethyleneureido-containing monomers,
cyanoacetoxy-containing monomers, acetoacetoxy-containing monomers, and
hydroxymethyl diacetone acrylamide; and
(d) about 1 to about 30 weight percent of a monomer selected from the group
consisting of ethylene, vinyl halides, vinylidene halides, vinyl acetate,
acrylate monomers having the formula
##STR16##
acrylamide monomers having the formula
##STR17##
alkenyl aromatic monomers, alkadiene monomers, and mixtures thereof,
wherein R.sub.12 is selected from the group consisting of hydrogen, alkyl
groups containing 1 to about 6 carbon atoms, and halo-substituted alkyl
groups containing 1 to about 6 carbon atoms, R.sub.13 and R.sub.14 are
each an alkyl group that independently contains up to about 18 carbon
atoms, and the monomers of (a)-(d) comprise at least 98 weight percent of
the monomers employed in forming the aqueous polymeric composition.
11. The aqueous polymeric composition of claim 10 formed by reacting the
substantially non-self-polymerizable monomer, the copolymerizable monomer,
the wet adhesion promoting monomer, and about 1 to about 30 weight percent
of the monomer (d) selected from the group consisting of vinyl halides,
vinylidene halides, vinyl acetate, acrylate monomers having the formula
##STR18##
acrylamide monomers having the formula
##STR19##
alkenyl aromatic monomers having the formula
##STR20##
wherein X is an aliphatic radical containing at least one alkenyl bond, Y
is a substituent on the aromatic ring, and n is an integer of from 0 to
about 5, alkadiene monomers having the formula
##STR21##
wherein R.sub.15, R.sub.16, R.sub.17, and R.sub.18 are each independently
selected from the group consisting of hydrogen, halogen, and alkyl
radicals containing 1 to about 2 carbon atoms, and mixtures thereof.
12. The aqueous polymeric composition of claim 9 formed by reacting about
45 to about 55 weight percent of the non-self-polymerizable monomer, and
about 45 to about 55 weight percent of the wet adhesion promoting monomer.
13. An aqueous polymeric composition formed by reacting in water and in the
presence of an initiator:
(a) 35 to about 65 weight percent of a substantially non-self-polymerizable
monomer selected from the group consisting of itaconic acid, maleic acid,
fumaric acid, and mixtures thereof;
(b) about 35 to about 65 weight percent of a wet adhesion promoting monomer
selected from the group consisting of ethyleneureido-containing monomers,
cyanoacetoxy-containing monomers, acetoacetoxy-containing monomers, and
hydroxymethyl diacetone acrylamide; and
(c) about 1 to about 30 weight percent of a monomer selected from the group
consisting of ethylene, vinyl halides, vinylidene halides, vinyl acetate,
acrylate monomers having the formula
##STR22##
acrylamide monomers having the formula
##STR23##
alkenyl aromatic monomers, alkadiene monomers, and mixtures thereof,
wherein R.sub.12 is selected from the group consisting of hydrogen, alkyl
groups containing 1 to about 6 carbon atoms, and halo-substituted alkyl
groups containing 1 to about 6 carbon atoms, R.sub.13 and R.sub.14 are
each an alkyl group that independently contains up to about 18 carbon
atoms, and the monomers of (a)-(c) comprise at least 98 weight percent of
the monomers employed in forming the aqueous polymeric composition.
14. The aqueous binder of claim 7 wherein the film former comprises a
monomer selected from the group consisting of ethylene, vinyl acetate,
acrylate monomers having the formula
##STR24##
acrylamide monomers having the formula
##STR25##
wherein R.sub.12 is selected from the group consisting of hydrogen, alkyl
groups containing 1 to about 6 carbon atoms, and halo-substituted alkyl
groups containing 1 to about 6 carbon atoms, and R.sub.13 and R.sub.14 are
each an alkyl group that independently contains up to about 18 carbon
atoms, alkenyl aromatic monomers having the formula
##STR26##
wherein X is an aliphatic radical containing at least one alkenyl bond, Y
is a substituent on the aromatic ring, and n is an integer of from 0 to
about 5, alkadiene monomers having the formula
##STR27##
wherein R.sub.15, R.sub.16, R.sub.17, and R.sub.18 are each independently
selected from the group consisting of hydrogen, halogen, and alkyl
radicals containing 1 to about 2 carbon atoms, and mixtures thereof.
15. The aqueous binder composition of claim 7 comprising about 0.7 to about
1.7 weight percent of the aqueous polymeric composition solids content and
about 98.3 to about 99.3 weight percent of the high molecular weight film
former.
16. The aqueous polymeric composition of claim 2 formed by reacting about
20 to about 30 weight percent of the non-self-polymerizable monomer, about
45 to about 60 weight percent of the copolymerizable monomer, and about 15
to about 30 weight percent of the wet adhesion promoting monomer.
17. An aqueous binder composition comprising:
(a) the aqueous polymeric composition of claim 9; and
(b) a high molecular weight film former, wherein the aqueous polymeric
composition has a solids content and, based upon the total solids content
of the aqueous binder composition, the aqueous binder composition
comprises about 0.5 to about 3 weight percent of the aqueous polymeric
composition solids content and about 97 to about 99.5 weight percent of
the high molecular weight film former.
Description
BACKGROUND
The present invention relates to polymer systems and, in particular, to
latex paints, binders for use in latex paints, processes for the synthesis
of binders, and polymeric components used in the binders.
Latex paints are a mixture of a multitude of ingredients. Typical
ingredients include coalescing aids, thickening aids, dispersing aids,
defoamers, biocides, pigments, and binders. The large numbers of
ingredients makes it difficult to formulate latex paints. In addition,
optional ingredients are also employed in latex formulations to enhance
various paint properties. For example, rheology modifiers are employed to
enhance a paint's film-build characteristics. Film-build is an indication
of a paint's hiding power, i.e., an indication of how well one coat of the
paint covers a surface. Since flat latex paints are generally applied over
a much larger surface area, e.g., wall and ceiling surfaces, than the
surface areas typically covered by semi-gloss latex paints, e.g., trim,
film-build characteristics are especially important in flat latex paints.
In addition, wet adhesion promoters are employed to enhance a paint's
adhesion to a surface. This is especially true in the case of paints
containing vinyl acrylic-type binders.
However, use of rheology modifiers and wet adhesion promoters in paint
formulations tends (a) to make it more difficult to formulate latex paints
and (b) to adversely affect other latex paint properties.
SUMMARY OF THE INVENTION
The present invention provides a latex paint capable of exhibiting good
film-build characteristics and good wet adhesion properties. The paint
inherently possesses good wet adhesion and, in certain embodiments, good
rheology so that the use of separate wet adhesion promoters and rheology
modifiers for improved film build is unnecessary. This result is achieved
by employing in the paint a binder that comprises about 97 to about 99.5
weight percent of a high molecular weight film former and about 0.5 to
about 3 weight percent of a particular polymer.
In one version of the invention, the polymer comprises about 15 to about 35
weight percent of a substantially non-self-polymerizable monomer, about 30
to about 70 weight percent of a copolymerizable monomer having a
water-soluble homopolymer, and about 10 to about 35 weight percent of a
wet adhesion promoting monomer. As used in the specification and claims,
the term "substantially non-self-polymerizable monomer" means a
copolymerizable monomer that does not give high yields (i.e., yields
greater than about 95 weight percent, and preferably greater than about 85
weight percent) of high molecular weight (i.e., greater than about 2,000
mw) homopolymer when reacted for about 3 hours at about 90.degree. C. in
the presence of about 1 weight percent potassium persulfate; and the term
"water-soluble homopolymer" means a homopolymer that is dissolvable in
water at a temperature of about 25.degree. C. and at a concentration of at
least about 25 g homopolymer per 100 ml water. This version of the
invention provides a paint that exhibits good rheology and good wet
adhesion are obtained.
In another version of the invention, the polymer comprises about 35 to
about 65 weight percent of the substantially non-self-polymerizable
monomer and about 35 to about 65 weight percent of the wet adhesion
promoting monomer. Good wet adhesion is exhibited by paints of this latter
embodiment. In both versions of the invention, the polymer and the film
former are substantially inseparable by chromatographic means.
The invention also encompasses an emulsion comprising water and the
polymer, a film formed by drying the paint, an article having a portion of
its surface coated with film, and a process for synthesizing the binder.
The binder synthesis process comprises the steps of forming the polymer and
polymerizing monomers in a reaction vessel to form the binder while delay
adding the polymer to the reaction vessel. The term "delay adding" is a
term of art that means adding ingredients during at least a portion of the
polymerization period.
DETAILED DESCRIPTION OF THE INVENTION
In one embodiment of the present invention, the polymer comprises about 15
to about 35 weight percent of a substantially non-self-polymerizable
monomer, about 30 to about 70 weight percent of a copolymerizable monomer
having a water-soluble homopolymer, and about 10 to about 35 weight
percent of a wet adhesion promoting monomer. In this version of the
invention, the polymer preferably comprises about 20 to about 30 weight
percent of the non-self-polymerizable monomer, about 40 to about 60 weight
percent of the copolymerizable monomer, and about 15 to about 30 weight
percent of the wet adhesion promoting monomer. More preferably, the
polymer comprises about 45 to about 55 weight percent of the
copolymerizable monomer.
In another embodiment of the invention, the polymer comprises about 35 to
about 65 weight percent of the non-self-polymerizable monomer and about 35
to about 65 weight percent of the wet adhesion promoting monomer. The
polymer of this embodiment preferably comprises about 45 to about 55
weight percent of the non-self-polymerizable monomer and about 45 to about
55 weight percent of the wet adhesion promoting monomer.
Exemplary non-self-polymerizable monomers include, but are not limited to,
compounds having the formula I
##STR1##
wherein R.sub.1 is hydroxy, alkoxy, or amino, R.sub.2 is hydrogen or
CH.sub.2 COZ.sub.1, R.sub.3 and R.sub.4 are independently hydrogen or
COZ.sub.2, and Z.sub.1 and Z.sub.2 are independently hydroxy, alkoxy, or
amino. Preferably, the compound of formula I contains no more that a total
of three, and more preferably no more than a total of two, amino and/or
carboxylic acid groups. Each alkoxy moiety generally contains from 1 to
about 8 carbon atoms, and preferably from 1 to about 2 carbon atoms. Most
preferably, R.sub.1, Z.sub.1, and Z.sub.2 are hydroxy. One or more
different compounds of formula I can be present in the polymer.
Illustrative compounds of formula I are itaconic acid, maleic acid, fumaric
acid, itaconate ester, maleate ester, dimethylmaleate, and fumarate ester.
Preferably, the non-self-polymerizable monomer is an acid-containing
monomer, and most preferably is itaconic acid.
Typical copolymerizable monomers include, but are not limited to, N-vinyl
lactams having the formula II
##STR2##
wherein m is an integer from about 3 to about 5 (preferably 3 or 4), and
acrylates having the formula III and acrylamides having the formula IV
##STR3##
wherein R.sub.5 and R.sub.6 are independently hydrogen or methyl, R.sub.7
is hydrogen or an alkyl group preferably containing 1 to about 30 carbon
atoms, n is an integer from 1 to about 30, and p is either 0 or 1. More
preferably, R.sub.7 is hydrogen or an alkyl group containing about 12 to
about 24 carbon atoms. When R.sub.7 is hydrogen, n is preferably 1, and
when R.sub.7 is an alkyl group containing about 12 to about 24 carbon
atoms, n is preferably within the range of about 20 to about 30.
The most preferred acrylates, and the most preferred copolymerizable
monomers are 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. In
addition, a single copolymerizable monomer or a mixture of the
copolymerizable monomers can be present in the polymer.
Wet adhesion promoting monomers include, but are not limited to
ethyleneureido-containing monomers, cyanoacetoxy-containing monomers,
acetoacetoxy-containing monomers, and hydroxymethyl diacetone acrylamide.
The ethyleneureido-containing monomers contain a ureido group of the
formula V:
##STR4##
Exemplary ethyleneureido-containing monomers include, but are not limited
to, 2-ethyleneureido-ethyl, acrylate, 2-ethyleneureido-ethyl acrylamide,
2-ethylemeureido-ethyl methacrylate,
1-[2-(3-allyloxy-2-hydroxypropylamino)ethyl]-imidazolidin-2-one. Mixtures
of ethyleneureido-containing monomers can be present in the polymer. A
commercially available ethyleneureido-containing monomer is
1-[2-(3-allyloxy-2-hydroxypropylamino)ethyl]-imidazolidin-2-one which is
commercially known as Sipomer WAM brand monomer available from Alcolac.
Cyanoacetoxy-containing monomers and acetoacetoxy-containing monomers have
the formulas VI and VII, respectively,
##STR5##
wherein R.sub.8 is selected from the group consisting of hydrogen and
halogen, R.sub.9 is selected from the group consisting of hydrogen, halo,
thio, and monovalent organic radicals, R.sub.10 is a divalent radical, and
R.sub.11 is selected from the group consisting of hydrogen and monovalent
organic radicals. As used throughout the specification and claims, the
term "organic radical" means any group containing at least one carbon
atom, and the term "inorganic radical" means any group devoid of carbon
atoms.
Preferably R.sub.8 is hydrogen, R.sub.9 is hydrogen or an alkyl radical
having up to about 10 carbon atoms, R.sub.10 is a cyclic or acyclic
organic radical containing up to about 40 carbon atoms, and R.sub.11 is an
acyclic organic radical containing up to about 15 carbon atoms. More
preferably, R.sub.10 is an acyclic radical containing up to about 20 atoms
in length, with any and all side groups each being up to about 6 length,
and R.sub.11 is hydrogen or an alkyl group containing up to about 7 carbon
atoms. R.sub.10 is most preferably alkylene and alkoxylene groups
containing up to about 10 carbon atoms, and R.sub.11 is most preferably
methyl. While acetoacetoxyethyl methacrylate, cyanoacetoxyethyl
methacrylate, and allylacetoacetate are reported in the literature, and
while acetoacetoxyethyl methacrylate and allylacetoacetate are commercial
availability, acetoacetoxyethyl methacrylate is the choice
acetoxy-containing monomer.
Optionally, the polymer comprises ethylene, a vinyl monomer, an acrylate
monomer, an acrylamide monomer, an alkenyl aromatic monomer, and/or an
alkadiene monomer. Typical vinyl monomers include, but are not limited to,
vinyl halides, vinylidene halides, vinyl acetate, and acrylonitrile.
Chlorine and bromine are exemplary halide moieties of vinyl halide and
vinylidene halide monomers.
The acrylate monomers generally have the formula VIII
##STR6##
and acrylamide monomers generally have the formula IX
##STR7##
wherein R.sub.12 is selected from the group consisting of hydrogen, alkyl
groups containing 1 to about 6 carbon atoms, and halo-substituted alkyl
groups containing 1 to about 6 carbon atoms, and R.sub.13 and R.sub.14 are
each an alkyl group independently containing up to about 18 carbon atoms.
Preferably, R.sub.12 is selected from the group containing hydrogen and
methyl, and R.sub.13 and R.sub.14 are each an alkyl group independently
containing up to about 8 carbon atoms. Preferred acrylate monomers are
selected from the group consisting of methyl acrylate, ethyl acrylate,
ethyl methacrylate, and mixtures thereof. Ethyl acrylamide and methyl
acrylamide, as well as mixtures of these two monomers, are the preferred
acrylamide monomers.
As used in the specification and claims, "alkenyl aromatic monomers" are
defined as any organic compound containing at least one aromatic ring and
at least one aliphatic-containing moiety having alkenyl unsaturation.
Preferred alkenyl aromatic monomers are represented by the formula X
##STR8##
wherein X is an aliphatic radical containing at least one alkenyl bond, Y
is a substituent on the aromatic ring, and n is the number of Y
substituents on the ring, n being an integer from 0 to 5. Generally, X
comprises at least 2 carbon atoms, but usually no more than about 6, and
preferably no more than about 3 carbon atoms. X is preferably a
substituted or unsubstituted alkenyl group. Preferred alkenyl group
substituents are halogen radicals, e.g., chloride. However, the most
preferred alkenyl group is unsubstituted, i.e., a hydrocarbon, and
contains only one olefinic unsaturation. Ethylene is the most preferred X.
Y is an organic or inorganic radical. When n is 2 or more, Y can be the
same or different. If organic, Y generally contains from 1 to about 15
carbon atoms and, preferably, is an aliphatic radical. Even more
preferably, Y is a saturated aliphatic radical. If inorganic, Y is
preferably a halogen. Exemplary Y substituents include halo and cyano
radicals and substituted and unsubstituted alkyl radicals of 1 to about 10
carbon atoms. Preferred Y substituents are chloride and unsubstituted
alkyl groups of 1 to about 6 carbon atoms. Y is more preferably a chloride
radical and C.sub.1 to about C.sub.4 unsubstituted alkyl radicals.
Illustrative alkenyl aromatic monomers include styrene, p-methyl styrene,
methyl styrene, o,p-dimethyl styrene, o,p-diethyl styrene,
p-chlorostyrene, isopropyl styrene, t-butyl styrene, o-methyl-p-isopropyl
styrene, o,p-dichlorostyrene, and mixture thereof. Due to its commercial
availability and low cost, styrene is the preferred alkenyl aromatic
monomers.
Exemplary alkadiene monomers have the formula XI
##STR9##
wherein R.sub.15, R.sub.16, R.sub.17, and R.sub.18 are each independently
selected from the group consisting of hydrogen, halogen, and alkyl
radicals containing 1 to about 2 carbon atoms. Commercially available
alkadiene monomers include butadiene, isoprene, 1,3-pentadiene, 2-ethyl
butadiene, and 4-methyl-1,3-pentadiene. The preferred alkadiene monomer is
butadiene.
Although the optional monomers can comprise up to about 30 weight of the
polymer, the optional monomers preferably comprise about 1 to about 20
weight percent of the polymer. The non-self-polymerizable monomer, the wet
adhesion promoting monomer, the copolymerizable monomer (when employed),
and optional monomers (when employed) together generally constitute at
least about 95 weight percent of the polymer, and preferably at least
about 98 weight percent of the polymer. In fact, it is frequently the case
that the only additional ingredients present in the polymer are substances
(e.g., surfactants, initiators) that are employed to aid in polymerizing
the monomers.
The polymer is made, for example, by charging the monomeric ingredients,
water, and a surfactant (when employed) into a reaction vessel, purging
the reaction vessel with an inert gas, e.g., nitrogen, to remove
essentially all the oxygen from the reactor vessel, and heating the
reactor vessel to the reaction temperature, e.g. from about 80.degree. to
about 100.degree. C. When the reactor vessel reaches the desired reaction
temperature, an initiator is then added to the reaction vessel, and the
reaction is continued for about 2 to about 4 hours. After the reaction is
completed, the reactor vessel is cooled. This synthesis yields an aqueous
polymeric composition comprising the polymer in water. In some instances,
the composition has the appearance of a milky emulsion, while in other
instances it looks like a clear solution.
Anionic, nonionic, and amphoteric surfactants can be employed in the
polymer synthesis process. Exemplary anionic, nonionic, and amphoteric
surfactants are Siponate A246L brand surfactant available from Alcolac,
polyoxyethylene alkyl phenol surfactants, and N,N-biscarboxyethyl
lauramine, respectively. However in some instances, no surfactant is
required.
Typical initiators include thermally generated free radical sources such as
persulfates, perphosphates, and hydrogen peroxide. Generally, the
initiator is employed in a concentration of about 0.5 to about 2 parts per
hundred parts monomer by weight (phm), and preferably in a concentration
of about 0.75 to about 1.25 phm.
The aqueous polymeric composition is used in the synthesis of a paint
binder. Typically, the binder comprises about 0.5 to about 3 weight
percent of the polymer and about 97 to about 99.5 weight percent of a high
molecular weight film former. Preferably, about 0.7 to about 1.7 weight
percent of the polymer and about 98.3 to about 99.3 weight percent of the
film former are present in the binder.
The high molecular weight film formers are typically made from monomers
selected from the group consisting of the above described ethylene and
vinyl monomers, acrylate monomers, acrylamide monomers, alkenyl aromatic
monomers, and alkadiene monomers.
A characteristic of the binder is that the polymer and film former are
substantially inseparable by chromatographic means. As is shown below in
the examples, this characteristic is important in enhancing the
wet-adhesion properties of a paint containing the binder.
Typically, the binder is formed by synthesizing the film former while
adding the polymer to the reaction medium during at least a portion of the
synthesis procedure. Preferably, the polymer is added to the reaction
medium during about the last 50 percent of the synthesis procedure, and
more preferably during the last 25 percent of the synthesis procedure.
More specifically, the binder is prepared by charging water, a surfactant
(e.g., anionic and nonionic surfactants), and a buffer (e.g., sodium
bicarbonate) into a reactor and then heating the reaction to the desired
reaction temperature, for example about 50.degree. to about 90.degree. C,
while purging the reactor with an inert gas, e.g. nitrogen. An initiator
system is then added to the reactor. The initiator system can be the above
described thermally generated free radical sources or a redox system
containing an oxidizing agent (e.g., hydrogen peroxide) and a reducing
agent (e.g., sodium metabisulfite or erythorbic acid).
A film-forming monomer and an additional amount of the initiator system are
then simultaneous fed into the reactor by separate feed streams. After a
period of time, typically at least about 25 percent of the reaction time,
the delay feed of the polymer is commenced. After all the monomer and
polymer have been added to the reactor, the reaction is continued for
about 15 minutes to about 1 hour and post-addition ingredients are then
added to the reactor to reduce any residual monomer concentration.
The resulting binder typically has a high shear viscosity of at least about
90 cps measured at about 25.degree. C. and about 12,000 sec.sup.-1 shear
rate. Preferably, the binder has a high shear viscosity of about 90 to
about 1,000 cps measured at about 25.degree. C and about 12,000 sec.sup.-1
shear rate. More preferably, the binder has a high shear viscosity of
about 100 to about 300 cps measured at about 25.degree. C. and about
12,000 sec.sup.-1 shear rate.
In addition, the binder typically has a low shear viscosity of about 100 to
about 3,500 cps measured at about 25.degree. C. and about 50 sec.sup.-1
shear rate. Preferably, the binder has a low shear viscosity of about 250
to about 1,000 cps measured at about 25.degree. C and about 50 sec.sup.-1
shear rate.
The binder of the present invention is most preferably employed in a paint.
Usually, paints have a solids content of at least about 50 percent by
volume, and more typically about 50 to about 65 percent by volume.
Generally, the paint comprises the binder, a pigment, and a carrier, e.g.,
water. In addition, the paint also typically comprises a coalescing aid, a
thickening aid, a dispersing aid, a defoamer, and a biocide.
Depending upon the intended use of the paint, the pigment volume
concentration (PVC) of the paint is generally less than about 35, or less
than about 30, and even less than about 20. Paints of the present
invention having a PVC content of about 20 to about 30 typically exhibit a
wet adhesion of at least about 400, and preferably at least about 2,000,
cycles wet scrub resistance on aged gloss alkyd paint.
In addition, the paint typically has a high shear viscosity of about 100 to
about 500 cps measured at about 25.degree. C. and about 12,000 sec.sup.-1
shear rate. Preferably, the paint has a high shear viscosity of about 150
to about 300 cps measured at about 25.degree. C. and about 12,000
sec.sup.-1 shear rate.
With respect to low shear viscosity, the paint typically has a low shear
viscosity of about 65 to about 110 Krebs units measured at about
25.degree. C., and preferably about 80 to about 100 Krebs units measured
at about 25.degree. C.
The paint is applied to at least a portion of a surface of a substrate and,
when dried, forms a film. For films made from paints having a PVC of at
least about 60, the films have a scrub resistance of at least about 100,
and preferably at least about 200, cycles abrasive scrub.
EXAMPLES
The following examples demonstrate the preparation of an exemplary polymer,
binder, and paint within the scope of the present invention. In order to
demonstrate the need to prepare the binder, in a manner such that its
constituent (i) polymer within the scope of the present invention and (ii)
film former are substantially inseparable by chromatographic means, one
example is provided that contrasts the properties of two very similar
paints. Both paints comprise a binder that contains the same film former
and the same polymer. The sole difference between the paints is that one
binder is made by polymerizing monomers in a reactor to synthesize the
film former while adding the polymer to the reactor during at least a
portion of the synthesis procedure. The other binder is made by simply
blending the polymer with a previously prepared film former.
EXAMPLE 1
Polymer Synthesis
Water (816 g), Siponate A246L brand anionic surfactant available from
Alcolac (19 g), 2-hydroxyethyl acrylate (56 g), itaconic acid (35 g),
Sipomer WAM brand adhesion promoter monomer (33 g), and vinyl acetate (28
g) were charged to a reactor. The contents of the reactor were mixed.
While purging the reactor with nitrogen, the reactor was heated to about
90.degree. C. When the reactor reached about 90.degree. C., an initiator
solution comprising about 13 g water and about 1.5 g sodium persulfate was
added to the reactor. The reaction was continued for about 3 hours and
then the reactor was cooled.
EXAMPLE 2
Synthesis of Chain-Entangled Binder
A binder was prepared by charging water (about 367 g), Alipal EP-110 brand
anionic surfactant available from GAF (about 99 g, 35% active), and sodium
bicarbonate about 2.6 g) to a reactor. The reactor was heated to about
70.degree. C. while purging the reactor with nitrogen. About 19 ml of an
initiator solution comprising about 71 g water and about 3.6 g potassium
persulfate was then added to the reactor. Afterwards, (i) the remaining
portion of the initiator solution and (ii) a monomer mixture containing
about 663 g vinyl acetate and about 117 g 2-ethylhexyl acrylate were added
to the reactor over a period of about 3 hours. Another feed, comprising
about 39 g water and about 120 g of the polymer of Example 1, was
simultaneously added to the reactor during about the last 1.5 hours of the
addition period.
After the addition of all 3 feeds was finished, the reactor was held at
about 70.degree. C. for about the next 30 minutes. Next, two post-addition
solutions were added to the reactor. One post-addition solution contained
about 7.8 g water and about 0.78 g tert-butyl hydrogen peroxide and the
other post-addition solution contained about 7.8 g water and about 0.78 g
hydro AWC brand reducing agent. The reactor was cooled after adding the
post-additive solutions.
EXAMPLE 3
Synthesis of Binder Devoid of Polymer
Another binder was prepared by the same procedure set forth in Example 2,
supra, with one modification, namely, the polymer of Example 1 was not
added at any time during the synthesis of the binder.
EXAMPLE 4
Preparation of Blended Binder
A binder prepared according to the procedure set forth in Example 3, supra,
was blended with about 120 g of the polymer of Example 1. The blending was
performed at ambient temperature using good mechanical mixing for about 20
to about 30 minutes. Afterwards, the blend was allowed to stand at ambient
temperature for about 18 hours.
EXAMPLES 5-7
Preparation of Semi-gloss Paints
Three semi-gloss paints (formulated at about 25 PVC) were each prepared by
combining propylene glycol, water, Natrosol 250 HR brand hydroxyethyl
cellulose (available from Aqualon), Colloid 681-F brand defoaming agent
(available from Colloids, Inc.), Tamol 731 brand dispersing aid (25
percent active; available from Rohm & Haas Co.), AMP-95 brand base
(available from Angus Chemical), Igepal CO-610 brand nonionic surfactant
(available from GAF), PMA-30 brand biocide (available from Troy Chemical),
and Tronox CR-800 brand titanium dioxide (available from Kerr-McGee) in
the proportion set forth in Table I below.
TABLE I
______________________________________
Material Weight, g Volume, ml
______________________________________
Propylene glycol
681.0 659.6
Water 2061.3 2061.3
Natrosol 250 HR 34.6 26.4
Colloid 681-F 9.9 11.5
Tamol 731 79.2 72.6
AMP-95 29.7 32.2
Igepal CO-610 19.8 18.1
PMA-30 9.9 8.2
Tronox CR-800 2474.6 604.4
______________________________________
The material combination listed in Table I was dispersed at a high speed to
a National Standard rating of about 7. Next, the ingredients set forth in
Table II were added to the ground mixture.
TABLE II
______________________________________
Material Weight, g Volume, ml
______________________________________
Texanol.sup.a 130.7 136.9
Colloid 681-F 19.8 23.1
Water 989.8 989.4
55% testing vinyl
3959.3 3627.9
acrylic.sup.b
Triton GR-5.sup.c
19.8 16.5
______________________________________
.sup.a Texanol brand coalescing aid (available from Eastman Kodak).
.sup.b The binder of Example 2, 3 or 4.
.sup.c Triton GR5 brand anionic surfactant (available from Rohm & Haas
Co.).
Each paint had the composition set forth in Table III and the physical
properties set forth in Table IV.
TABLE III
______________________________________
Paint Formulation
Weight, g
______________________________________
Paste 92.40
Texanol 2.24
Colloid 681-F 0.34
Water 16.94
55% TS Latex.sup.d
67.75
Triton GR-5 0.34
Total Weight 180.00 g
Total Volume 141.84 ml
______________________________________
.sup.d TS denotes "total solids".
TABLE IV
______________________________________
Physical Properties
______________________________________
Viscosity, KU 73-85
Density 10.57 lbs/gal
P.V.C. 24.7%
% Solids
By Weight 44.5%
By Volume 29.9%
pH 9.5+/-0.5
______________________________________
EXAMPLES 8-10
Preparation of Flat Paints
Three flat paints (having a PVC content of about 60) were each prepared by
combining water, Natrosol 250 HR brand hydroxyethyl cellulose, AMP-95
brand base, Tamol 731 brand dispersing aid, Igepal CO-630 brand nonionic
surfactant, ethylene glycol, Colloidal 681-F brand defoamer, Super Ad-it
brand biocide (available from Huls-America), Tronox CR-801 brand titanium
dioxide, Satin Tone #1 brand extender (available from Engelhard), and
Snowflake brand extender (available from ECC America) in the proportions
set forth in Table V below.
TABLE V
______________________________________
Material Weight, g Volume, ml
______________________________________
Water 2131.5 2131.4
Natrosol 250 HR 25.0 19.5
AMP-95 19.5 20.9
Tamol 731 27.8 25.0
Igepal CO-630 16.7 15.8
Ethylene Glycol 103.5 92.7
Colloid 681-F 11.1 12.0
Super Ad-it 5.6 5.1
Tronox CR-801 1112.5 276.6
Satin Tone #1 834.4 317.4
Snowflake 1112.5 411.9
______________________________________
The material combination listed in Table V was ground at a high speed to a
National Standard rating of about 4. Next, Texanol brand coalescing aid,
Colloidal 681-F brand defoamer, and 55% testing vinyl acrylic were added
to the ground mixture in the proportions stated in Table VI below.
TABLE VI
______________________________________
Material Weight, g Volume, ml
______________________________________
Texanol 38.9 40.8
Colloid 681-F 11.1 12.0
55% testing vinyl
1418.4 1312.7
acrylic
______________________________________
Each paint had the formulation and physical properties set forth in Tables
VII and VIII, respectively.
TABLE VII
______________________________________
Paint Formulation
Weight, g
______________________________________
Paste 196.52
Texanol 1.42
Colloid 681-F 0.41
55% TS Latex 51.66
Total Weight 250.00 g
Total Volume 170.70 ml
______________________________________
TABLE VIII
______________________________________
Physical Properties
______________________________________
Viscosity, KU 85-95
Density 12.2 lbs/gal
P.V.C. 60%
% Solids
By Weight 56.3%
By Volume 36.1%
pH 9.5+/-0.5
______________________________________
EXAMPLES 11-13
Wet Adhesion Test
Wet adhesion tests were conducted according to the procedure described in
Appendix A. The results of the wet adhesion test are set forth in Table
IX, infra.
TABLE IX
______________________________________
Paint
Binder Semi-gloss
Par- Wet
TS ticle
Adhe- Krebs Flat
Ex. %.sup.a
pH Size.sup.b
sion.sup.c
Visc.sup.d
Scrub.sup.e
______________________________________
2 55.2 3.82 348 184 76 0.74
3 55.1 4.41 122 19 69 0.34
4 ND.sup.f
ND ND 3 86 0.30
______________________________________
.sup.a TS % denotes weight percent total solids.
.sup.b Particle size measured in nm.
.sup.c Wet adhesion measured in terms of cycles wet scrub resistance on
aged gloss alkyd paint.
.sup.d Krebs Visc denotes Krebs Viscosity measured in Krebs Units at abou
25.degree. C.
.sup.e Scrub measured in terms of percent of a commercial standard
(76RES3077 [UNOCAL]).
.sup.f ND denotes "not determined.
As seen from Table IX, a semi-gloss paint prepared using the
chain-entangled binder of Example 2 exhibits a remarkably improved wet
adhesion when compared to paint formulations that only differ in that
their binder is either devoid of a polymer within the scope of present
invention (Example 3's binder) or prepared by blending the film former
with the polymer (Example 4's binder).
EXAMPLES 14-17
High-Shear Viscosity
The high-shear viscosity of each paint formulation was determined using an
ICI cone and plate viscometer according to the manufacturer's
instructions. The results of these tests are set forth in Table IX, supra.
As shown in Table IX, a paint employing the chain-entangled binder of
Example 2 has a high shear or ICI viscosity substantially improved over
paint formulations that only differ in that their binder is either devoid
of a polymer within the scope of present invention or prepared by blending
the film former with the polymer.
EXAMPLES 18-19
Scrub Test
The ability of each paint formation to withstand scrubbing was determined
accordingly to ASTM Method D-2486-79, this publication being incorporated
herein in its entirety by reference. The results of the scrub test are
indicated in the above Table IX. The data indicate that paints prepared
with the chain-entangled binder of Example 2 have a scrub resistance over
twice that of paints prepared with either a binder that is devoid of a
polymer of the present invention or with a binder prepared by blending a
film former and the polymer.
Accordingly, improved wet adhesion, ICI viscosity, and scrub resistance are
exhibited by paint formulations incorporating binders prepared by
delay-adding polymers within the scope of the present invention during the
synthesis of the binder or otherwise making the polymer and the film
former component of the binder physically inseparable from each other.
Although the present invention has been described in considerable detail
with reference to certain preferred versions thereof, other versions are
possible. For example, a paint can include one or more ingredients that
enhance other paint properties. Therefore, the spirit and scope of the
appended claims should not necessarily be limited to the description of
the preferred embodiments contained herein.
APPENDIX A
Wet-Adhesion/Underwater Scrub Resistance
1. SCOPE. This method tests the adhesion of a latex gloss or semi-gloss
paint to an alkyd substrate when scrubbed underwater.
2. METHOD SUMMARY. Test films are cast side-by-side over a cured alkyl
substrate and allowed to dry. The dry films are cut through with a razor
blade and the panels are tested for underwater adhesion and scrub
resistance on a standard laboratory scrub tester. The films are scrubbed
underwater for 2000 cycles or until failure occurs. To pass, there shall
be no evidence of failure of adhesion between the test paint film and the
alkyl undercoat through 2000 scrub cycles (4000 brush strokes).
3. APPARATUS AND MATERIALS
Vacuum Plate
Leneta Black Scrub Test Panel (Form P121-10N)
Black Alkyd Enamel Paint (conforming to TT-E-489)
6-Inch Wide 6-mil Doctor Blade Applicator
3-Inch Wide 3-mil Doctor Blade Applicator
New Single-Edge Razor Blade
Gardner Straight-Line Washability and Abrasion Machine (Described in method
6141 of Fed. Test Method Std. No. 141)
Natural-Bristle Scrub-Brush and Holder (Described in method 6142 of Fed.
Test Method Std. No. 141)
Tap Water
Ruler with 1/4-inch divisions
4. PROCEDURE
4.1 SUBSTRATE. All films are cast with the substrate panel held securely on
a vacuum plate. On a Leneta Black Scrub Test Panel (Form P121-10N), a
black alkyd enamel conforming to TT-E-489 is cast length-wise in a
six-inch-side film using a 6-mil doctor blade applicator. The film is
allowed to cure at 77.degree. F..+-.3.degree. F. and 50%.+-.5% relative
humidity for a period of not less than six weeks and not more than 3
months, prior to the application of the test paint.
4.2 SAMPLE FILMS. The test paint is usually applied side-by-side with a
latex paint standard. Using a 3-inch wide 6-mil doctor blade applicator,
the two samples are applied width-wise across the alkyd substrate,
centered left-to-right and one inch apart. Two panels are prepared for
each test paint: one with the standard on the left and the test sample on
the right, and the other with the standard and sample reversed. The test
films are allowed to cure at 77.degree. F..+-.3.degree. F. and 50%.+-.5%
relative humidity for a period of three days prior to undergoing the test
procedures.
4.3 TESTING. With the plastic panel sitting flat on a hard, smooth surface,
a new single-edge razor blade is used to cut through each test film, down
the center along the axis on which it was drawn. Care should be taken not
to cut through the plastic panel, as well. The Leneta test panel is
clamped into the trough of a Gardner Straight-Line Washability and
Abrasion Machine) FTMS No. 141, Method 6141). Tap water is added to the
trough until the test (FTMS No. 141, Method 6142) is placed in an
appropriate holder and hooked up to the cables of the machine. The machine
is started and is run continuously for 2000 scrub cycles (4000 brush
strokes) or until each test film has broken.
5. CALCULATIONS. A film is deemed to have failed, or "broken," when it has
peeled back more than 1/4 inch from the razor cut. Data should be reported
as "pass" (sample demonstrated no peel-back over 2000 scrub cycles),
"partial failure" (sample ran 2000 cycles and suffered less than 1/4-inch
peel-back), or "failed at xxx cycles" (sample suffered greater than
1/4-inch peel-back at the given number of cycles). Another option would be
to report data as "2000+ cycles" for passing samples and partial failures,
and "xxx cycles" for failing samples.
6. PRECISION AND ACCURACY. The two test results for each sample (one from
each of the two prepared panels) should agree within a 25% confidency
margin. A difference of greater than 25% between the two values does not
support reproducability of the test.
7. REMARKS. The purpose in choosing the film applicator bars as indicated
is to achieve--with both the alkyd substrate and with the sample
films--dry films about 4 mils thick.
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